Many types of electrochemical cells utilize a liquid ionically conductive medium to support electrochemical reactions within the cell. Electrochemical cells may utilize an air breathing electrode coupled to a fuel electrode, comprising any suitable fuel. For example, a metal-air electrochemical cell system may comprise a plurality of cells, each having a fuel electrode serving as an anode at which metal fuel is oxidized, and an air breathing oxidant reduction electrode at which oxygen from ambient air is reduced. The liquid ionically conductive medium in such cells may communicate the oxidized/reduced ions between the electrodes.
In various ionically conductive mediums, evaporation, electrolysis (e.g. water splitting on recharge) or other loss of moisture from the ionically conductive medium, may be detrimental to the electrochemical cell particularly for cells requiring water to operate. For example, salting of the ionically conductive medium may clog an oxidant electrode of the electrochemical cell, reducing its performance or in extreme cases, result in complete cell failure. Such salting or other failures may occur, for example, where an air-side of the oxidant electrode, or a portion thereof, is excessively dry. Additionally, a decrease in water content in the ionically conductive medium may decrease the medium's solvating capacity, i.e., its ability to dissolve solutes, or increase the percentage concentration of solutes in the medium.
Systems have been developed for managing electrochemical cells. U.S. Patent Publication No. 20140227615, filed Feb. 10, 2014 and from the same Applicant, provides an example of a battery water management system, which is hereby incorporated by reference in its entirely.
This disclosure provides for a water management system to maintain water content in any electrochemical cell comprising a liquid ionically conductive medium without the need for pumps, liquid water reservoirs and mechanical level-control valves.